How to keep driver control objects in view of camera
You can add a custom property to an object and have them drive your animation:



The trick is to enable the little pin in the upper left corner. That way the editor keeps displaying that panel.

If you want controls moving with the camera, you can parent them to the camera, disable rendering for them in the Outliner and use local space instead of world space in the driver variables. That way only relative movement towards the camera affects your animation and the camera can still move around.

I recommend empties between the camera and the controls. The empties swallow the offset between control and the camera and the controls start with zero regarding their parent empty. That means you don't have to use awkward offset values in the driver.